/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.catalina.authenticator;

import org.apache.catalina.connector.Request;
import org.apache.catalina.deploy.LoginConfig;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.security.Principal;
import java.security.cert.X509Certificate;

/**
 * An <b>Authenticator</b> and <b>Valve</b> implementation of authentication
 * that utilizes SSL certificates to identify client users.
 *
 * @author Craig R. McClanahan
 */

public class SSLAuthenticator
		extends AuthenticatorBase {


	// ------------------------------------------------------------- Properties

	/**
	 * Descriptive information about this implementation.
	 */
	protected static final String info =
			"org.apache.catalina.authenticator.SSLAuthenticator/1.0";

	/**
	 * Return descriptive information about this Valve implementation.
	 */
	@Override
	public String getInfo() {

		return (info);

	}


	// --------------------------------------------------------- Public Methods

	/**
	 * Authenticate the user by checking for the existence of a certificate
	 * chain, validating it against the trust manager for the connector and then
	 * validating the user's identity against the configured Realm.
	 *
	 * @param request  Request we are processing
	 * @param response Response we are creating
	 * @param config   Login configuration describing how authentication
	 *                 should be performed
	 * @throws IOException if an input/output error occurs
	 */
	@Override
	public boolean authenticate(Request request,
	                            HttpServletResponse response,
	                            LoginConfig config)
			throws IOException {

		// NOTE: We don't try to reauthenticate using any existing SSO session,
		// because that will only work if the original authentication was
		// BASIC or FORM, which are less secure than the CLIENT-CERT auth-type
		// specified for this webapp
		//
		// Change to true below to allow previous FORM or BASIC authentications
		// to authenticate users for this webapp
		// TODO make this a configurable attribute (in SingleSignOn??)
		if (checkForCachedAuthentication(request, response, false)) {
			return true;
		}

		// Retrieve the certificate chain for this client
		if (containerLog.isDebugEnabled())
			containerLog.debug(" Looking up certificates");

		X509Certificate certs[] = getRequestCertificates(request);

		if ((certs == null) || (certs.length < 1)) {
			if (containerLog.isDebugEnabled())
				containerLog.debug("  No certificates included with this request");
			response.sendError(HttpServletResponse.SC_UNAUTHORIZED,
					sm.getString("authenticator.certificates"));
			return false;
		}

		// Authenticate the specified certificate chain
		Principal principal = context.getRealm().authenticate(certs);
		if (principal == null) {
			if (containerLog.isDebugEnabled())
				containerLog.debug("  Realm.authenticate() returned false");
			response.sendError(HttpServletResponse.SC_UNAUTHORIZED,
					sm.getString("authenticator.unauthorized"));
			return (false);
		}

		// Cache the principal (if requested) and record this authentication
		register(request, response, principal,
				HttpServletRequest.CLIENT_CERT_AUTH, null, null);
		return (true);

	}

	@Override
	protected String getAuthMethod() {
		return HttpServletRequest.CLIENT_CERT_AUTH;
	}
}
